There's a new weapon to fight poachers who kill elephants, hippos, rhinos and other wildlife - nuclear bombs.
By measuring radioactive carbon-14 deposited in tusks and teeth by open-air nuclear bomb tests, researchers can pinpoint the year an animal died, which discloses if the ivory was taken illegally.
The method uses the "bomb curve," which is a graph – shaped roughly like an inverted "V" – showing changes in carbon-14 levels in the atmosphere – and thus absorbed by plants and animals in the food chain. The carbon-14 was formed in the atmosphere by U.S. and Soviet atmospheric nuclear weapons tests in Nevada and Siberia from 1952 through 1962. Those levels peaked in the 1960s and have declined ever since but still are absorbed by and measurable in plant and animal tissues.
"This could be used in specific cases of ivory seizures to determine when the ivory was obtained and thus whether it is legal," says University of Utah geochemist Thure Cerling, senior author of a study about the new method.
"The dating method is affordable and accessible to government and law enforcement agencies," costing about $500 per sample, says the study's first author, geochemist Kevin Uno,
a postdoctoral researcher at Columbia University's Lamont-Doherty Earth Observatory.
"It has immediate applications to fighting the illegal sale and trade of ivory that has led to the highest rate of poaching seen in decades."
Not only can the method help wildlife forensics to combat poaching, but "we've shown that you can use the signature in animal tissues left over from nuclear weapons testing in the atmosphere to study modern ecology and help us learn about fossil animals and how they lived," says Cerling.
Ivory Trade Drives Elephant Slaughter
International agreements banned most trade of raw ivory from Asian elephants after 1975 and African elephants after 1989. In the United States, raw and worked African ivory (jewelry, figurines, gun and knife handles) is legal if it was imported before 1989 or, if worked ivory is imported after, it must be at least 100 years old.
Yet tons of illegal ivory still are sold because dealers claim the ivory was taken before the ban and there has been no test to prove them wrong – until now.
"With an accurate age of the ivory, we can verify if the trade is legal or not" when the age is combined with existing DNA analysis to determine if an elephant is from Africa or Asia, says Uno, who earned his University of Utah Ph.D. last year. "Currently 30,000 elephants a year are slaughtered for their tusks, so there is a desperate need to enforce the international trade ban and reduce demand."
Only 423,000 African elephants are left. Conservation groups say 70 percent of smuggled ivory goes to China. The United States is the next biggest illegal market. Rising ivory prices have drawn organized crime and spurred militias in Darfur, Uganda, Sudan and Somalia to kill elephants and sell tusks so they can buy guns.
This African elephant has what are believed to be the biggest tusks among elephants at Kenya's Samburu National Reserve. Illegal poaching of some 30,000 elephants a year for their ivory tusks threatens the animals with extinction. University of Utah geochemists developed a new way to fight poaching of elephants, hippos, rhinos and other animals. Carbon-14 from 1950s and 1960s nuclear weapons tests was and still is deposited in animals' tusks or teeth, and those carbon-14 levels reveal the year an animal died, and thus whether the ivory was taken before or after international bans on ivory trading. Credit: Thure Cerling, University of Utah.